Surface segregation in multicomponent high entropy alloys: Atomistic simulations versus a multilayer analytical model

TL;DR

This study compares atomistic simulations and a new multilayer analytical model to investigate surface segregation in high entropy alloys, demonstrating that the analytical approach offers rapid, qualitative insights useful for initial screening.

Contribution

The paper introduces a novel multilayer analytical model for N-component alloys and compares it with atomistic simulations, showing good qualitative agreement and potential for efficient alloy design.

Findings

Analytical model runs in seconds on a laptop.

Qualitative agreement between simulations and analytical results.

Analytical model useful for initial composition screening.

Abstract

This paper compares two approaches for investigating the near-surface composition profile that results from surface segregation in the so-called Cantor alloy, an equi-molar alloy of CoCrFeMnNi. One approach consists of atomistic computer simulations by a combination of Monte Carlo, molecular dynamics and molecular statics techniques, and the other is a nearest neighbor analytical calculation performed in the regular solution approximation with a multilayer model, developed here for the first time for a N-component system and tested for the 5-component Cantor alloy. This type of comparison is useful because a typical computer simulation requires the use of ~100 parallel processors for 2 to 3 hours, whereas a similar calculation by means of the analytical model can be performed in a few seconds on a laptop machine. The results obtained show qualitatively good agreement between the two approaches. Thus, while the results of the computer simulations are presumably more reliable, and provide an atomic scale picture, if massive computations are required, for example, in order to optimize the composition of a multicomponent alloy, then an initial screening of the composition space by the analytical model could provide a highly useful means of narrowing the regions of interest, in the same way that the CALPHAD method allows rapid investigation of phase diagrams in complex multinary systems.